Flow measurement is an important tool in medical diagnostic procedures, for example, in urology matters. In such measurements, the urinary output of a patient is monitored as a means to study operation of the patients bladder and urethral dysfunctions or obstructions for example.
It has been shown that measuring the urinary output of patients in an ambulatory manner, the patients being out of the hospital and ideally at home, yields results that are most representative of the reality of the patients and of their daily life, unaltered by any stress that may be caused by being confined in an institutional environment such as an hospital for example.
A number of uroflowmeters are known in the art. For example, West et al., U.S. Pat. No. 5,176,148, disclose an uroflowmeter comprising a container supporting a measuring head, which includes a funnel leading to an intake chamber. The intake chamber communicates by a bottom part thereof to a first chamber containing a pressure measuring tube and to a second chamber connected at a top hereof to a first pressure sensor of a pressure sensor unit, in such a way that a lower edge of a vertical slot of the pressure measuring tube, of the intake chamber and of the second chamber are located in a common horizontal plane. A measuring tube extending from the measuring head to the container in a direction parallel to the pressure measuring tube, is connected to a second pressure sensor of the pressure sensor unit. The second pressure senior measures a filling height of urine in the container via an air column in the measuring tube, while the first pressure sensor measures a column height in the intake chamber via an air column in the second chamber, which allows to obtain, on the basis on an outflow of urine through the pressure measuring tube, the flow of urine.
Jespersen, in U.S. Pat. No. 4,343,316, describes an uroflowmeter comprising a volumetric calibrated container receiving an inlet tube, itself connected upstream to a catheter, and connected to a urine drainage bag by an outlet tube. The volumetric calibrated container has a double cone shape so as to allow for an amount of vertical misalignment thereof. An optical sensor allows visually monitoring a building up of urine into the container, thereby yielding a flow per unit time, and dumping thereof into the urine drainage bag.
Carter et al., in U.S. Pat. No. 4,554,687, teach a toilet-mounted uroflowmeter comprising a container fitting into a toilet bowl, and which is connected to a pressure sensor by a tube. A height of fluid in the container is associated with an air pressure sent to the pressure sensor by a tube, and thereby to a flow rate in the container.
In spite of these technological efforts, currently available uroflowmeters are bulky devices and establishing micturition calendars remains a mainly manual task, inherently prone to errors.
Therefore, there is a need in the art for an ambulatory device for measuring urine flow, which is easy to use by a patient and in a way that permits accuracy of results and a full processing of individual variations related to a given patient as well as an historical tracking of the patients urinary activities for establishing micturition calendars.